Question

Among the following, the molecule that will have the highest dipole moment is:

• A. H$_2$
• B. HI
• C. HBr
• D. HCl
• E. HF

Hint:

Trend for dipole moment: $\text{HF}>\text{HCl}>\text{HBr}>\text{HI}$. Always check the electronegativity difference for diatomic molecules.

Answer 1

Answer: (E)

To determine which molecule has the highest dipole moment among the given options, we need to understand the concept of dipole moment and the factors that influence it.

The dipole moment (\( \mu \)) is defined as the product of the magnitude of the charge and the distance between the centers of positive and negative charges. It is represented mathematically as:

\(\mu = q \cdot d\)

where:

• \( q \) is the charge.
• \( d \) is the distance between the charges.

The dipole moment is a vector quantity and is usually measured in Debye units (D).

Now, let's analyze each molecule provided in the options:

1. H₂: This is a homonuclear diatomic molecule. The electronegativity difference between the two hydrogen atoms is zero, leading to no dipole moment. Thus, \(\mu = 0\) D.
2. HI: Hydrogen Iodide has a small electronegativity difference between H and I. Hence, its dipole moment is relatively low.
3. HBr: Hydrogen Bromide has a moderate electronegativity difference between H and Br, greater than HI but less than HCl and HF.
4. HCl: Hydrogen Chloride has a higher electronegativity difference than HI and HBr, leading to a larger dipole moment than both.
5. HF: Hydrogen Fluoride has the highest electronegativity difference among these molecules because fluorine is the most electronegative element. Consequently, HF has the largest dipole moment.

Comparing all the options, the molecule HF has the highest electronegativity difference, resulting in the highest dipole moment.

Thus, the correct answer is HF.